Geoscientific Instrumentation Methods and Data Systems Antarctic ozone variability inside the Polar Vortex estimated from balloon measurements

Abstract

Correspondence to: M. C. Parrondo (parrondosc@inta.es) Published by Copernicus Publications on behalf of the European Geosciences Union. 15663 Abstract 13 yr of ozonesoundings at the Antarctic Belgrano II station (78 • S, 34.6 • W) have been analyzed to establish a climatology of stratospheric ozone and temperature over the area. The station is inside the polar vortex during the period of development of chemi-cal ozone depletion. Weekly periodic profiles provide a suitable database for seasonal 5 characterization of the evolution of stratospheric ozone, especially valuable during win-ter time when satellites and ground-based instruments based on solar radiation are lacking. The work is focused on ozone loss rate variability (August–October) and its re-covery (November–December) at different layers identified according to the severity of ozone loss. The time window selected for the calculations covers the phase of a quasi-10 linear ozone reduction, about day 220 (mid August) to day 273 (end of September). Decrease of the total ozone column over Belgrano during spring is highly dependent on the meteorological conditions. Largest depletions (up to 59 %) are reached in cold-est years while warms winters exhibit significantly lower ozone loss (20 %). It has been found that about 11 % of the total O 3 loss in the layer where maximum depletion oc-15 curs takes place before the sun has arrived as a result of transport of lower latitude air masses, providing evidence of mixing inside the vortex. Spatial homogeneity of the vor-tex has been examined by comparing Belgrano results with those previously obtained for South Pole Station (SPS) for the same altitude range and for 9 yr of overlapping data. Unexpected results show more than 25 % larger ozone loss rate at SPS than at 20 Belgrano. It has been found that the accumulated hours of sunlight are the dominant factor driving the ozone loss rate. According to the variability of the ozone-hole recov-ery, a clear connection between the timing of the breakup of the vortex and the monthly ozone content was found. Minimum ozone concentration of 57 DU in the 12–24 km layer remained in November for the longest vortex, while years when the final stratospheric 25 warming took " very early " , mean integrated ozone rises up to 160–180 DU.